class ActiveRecord::ConnectionAdapters::ConnectionPool

ActiveRecord's connection pool is based on threads. Since we are working with EM and a single thread, multiple fiber design, we need to provide our own connection pool that keys off of Fiber.current so that different fibers running in the same thread don't try to use the same connection.

Public Class Methods

new(spec) click to toggle source
# File lib/active_record/fiber_patches.rb, line 52
def initialize(spec)
  @spec = spec

  # The cache of reserved connections mapped to threads
  @reserved_connections = {}

  # The mutex used to synchronize pool access
  @connection_mutex = FiberedMonitor.new
  @queue = @connection_mutex.new_cond

  # default 5 second timeout unless on ruby 1.9
  @timeout = spec.config[:wait_timeout] || 5

  # default max pool size to 5
  @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5

  @connections = []
  @checked_out = []
  @automatic_reconnect = true
  @tables = {}

  @columns     = Hash.new do |h, table_name|
    h[table_name] = with_connection do |conn|

      # Fetch a list of columns
      conn.columns(table_name, "#{table_name} Columns").tap do |columns|

        # set primary key information
        columns.each do |column|
          column.primary = column.name == primary_keys[table_name]
        end
      end
    end
  end

  @columns_hash = Hash.new do |h, table_name|
    h[table_name] = Hash[columns[table_name].map { |col|
      [col.name, col]
    }]
  end

  @primary_keys = Hash.new do |h, table_name|
    h[table_name] = with_connection do |conn|
      table_exists?(table_name) ? conn.primary_key(table_name) : 'id'
    end
  end
end

Public Instance Methods

clear_stale_cached_connections!() click to toggle source
# File lib/active_record/fiber_patches.rb, line 100
def clear_stale_cached_connections!
  cache = @reserved_connections
  keys = Set.new(cache.keys)

  ActiveRecord::ConnectionAdapters.fiber_pools.each do |pool|
    pool.busy_fibers.each_pair do |object_id, fiber|
      keys.delete(object_id)
    end
  end

  keys.each do |key|
    next unless cache.has_key?(key)
    checkin cache[key]
    cache.delete(key)
  end
end